The present invention relates generally to methods and apparatus for distributed optical sensing of acoustic or mechanical energy, and more particularly relates to systems and methods using a sensing system including a plurality of sensors coupled to one or more optical fibers, and also to a broadband pulsed light source suitable for use in such a system.
Systems that sense acoustic or mechanical energy are used in a variety of applications, including, but not limited to, oilfield drilling and maintenance, underwater monitoring, and maintenance of large structures, such as mines, bridges and elevators. In these sensing systems, sensors take measurements at their respective locations. The measurements taken by the sensors are compiled and may be used to provide information regarding the structure(s) or locations that are monitored.
One class of sensor is optical in nature. An optical sensor can generate optical signals, and can direct the measured information to the processor via one or more optical fibers. One issue facing some optical fiber-based sensing systems is channel count. In one approach, respective sensors can be optically coupled to optical excitation or detection apparatus, such as using a one-to-one arrangement including a respective optical fiber for each sensor. However, such an approach may preclude use of more than a handful of optical sensing channels, because the number of optical fibers or channels may be limited due to cost or space constraints. For example, in a downhole application, a cross-sectional area available for optical fiber assemblies may be limited, and interconnect complexity between respective fibers and other portions of the sensing system may preclude large channel counts without compromising reliability.
For optical fiber-based sensing systems, it would be desirable to have a system that has a relatively high channel count while providing immunity to harsh environmental conditions, such as for use in geophysical, petrophysical, and structural applications, such as oil exploration and recovery. Furthermore, it would be desirable to have a broadband, pulsed, high-powered light source that may be used with such a system.